okay, next step...what is your record selection formula?
you have no group selection filter so we can eliminate that as a potential issue.
you've copied the ShowSQL query and it runs fine in your query editor and returns actual values...this means your table linking is probably okay as that will be reflected in your show sql. however, if you've got pieces in your filter that are not being passed to the db server then that may be an issue.
things that don't get passed to the server are lines where you're manipulating fields with functions...e.g. year({your datefield}) = 2012
what all this means is that your Show SQL Query is not necessarily what the report is processing as far as the Record Selection. your report may be doing further filtering on your {MyTable1.Field1} field.